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Chapter 1 of this thesis is a general review of published work o_ the origins and distribution of Cd, Cu, Fe, Mn and Zn in soils and their uptake and functions in plants. Chapter 2 is a synopsis of the geological history of the Fayoum of relevance to the origins of sediments at the study sties. Previous fractionation procedures, and a proposed modification to improve the determination of carbonate-bound elements are discussed in Chapter 3, while other analytical procedures are described in Chapter 4. Results of general soil analyses, of the fractionation analyses and useful correlation matrices, are tabulated together (for convenience in Chapter 5) and are discussed in detail in the following chapter. Texture was a crucial factor, finer-textured soils generally having lower pH and higher organic matter contents, although the latter were generally greater closer to the surface. Clay and silt contents were highly correlated, probably reflecting water sorting in the Fayoum, which aided the texture/drainage effect. Drainage (i.e. texture) was apparently very important in the fractionation chemistry of elements influenced by redox-reactions, i.e. Fe and Mn, and elements for which distribution depended upon Fe and Mn oxides (e.g., Zn) to a significant extent. Clay was especially important to the concentration of crystalline and amorphous iron oxides. Cd and Cu showed marked surface accumulation, especially in the exchangeable fractions, for many profiles, probably through pollution. The Cu content of organic matter was strikingly uniform at the Fayoum. Amorphous and crystalline Fe oxides seem to be especially important in the distribution of Zn. Clay Cd, Fe and Zn and, to a lesser extent, Cu and Mn contents were relatively constant, suggesting uniform origins. Chapter 7 describes a pot experiment on the soils using barley as a test crop, aimed at relating uptake to the fractionation results. Interpretation was complicated by a dominant effect of soil salinity. Chapter 8 suggests future related research.

Work was undertaken to determine the efficiency of growing lambs offered a fixed amount of roughage and concentrate as; 1) a mixed diet (M), containing 500 g/kg DM roughage and 500 g/kg DM concentrate, 2) split feeds (S), roughage alone followed by concentrate alone, 3) a mixture changing from roughage to concentrate (R-C), or concentrate to roughage (C-R), or 4) half the animals offered roughage and half concentrate (R/C). Lamb growth was predicted from computer models based on current feeding standards. In experiment (1), lambs were offered 50 kg roughage DM and 50 kg concentrate DM by strategies M and S. Lambs on strategy S took longer to consume their food and maintained a higher EBW ^0.75 than those on strategy M. However, the final EBW and EB composition of the two groups was similar. This contrasted with predicted results. The higher overall efficiency of lambs on strategy S was explained partly by associative effects reducing the energy available to lambs on strategy M, and partly by a higher efficiency of energy utilisation and/or a lower maintainance requirement of lambs on strategy S. In experiment (2), the influence of associative effects on strategies R-C and C-R was investigated. The prediction of dry matter digestibility (DMD, Y) from concentrate proportion (CONCP, X1) and dry matter intake (X2) showed no curvilinearity. DMD was linearly related to CONCP. The equations derived for each strategy were similar. In experiment (3), lambs were offered 52.5 kg roughage DM and 52.5 kg concentrate DM by strategies M, R-C, C-R and R/C. Lambs on strategies R-C, C-R and R/C took a similar time to consume their food and achieved a similar final EBW and EB composition. Their energy retention (ER) was similar to that predicted. Lambs on strategy M consumed their food faster than those on all other strategies and achieved a higher (NS) EBW, which contained more (NS) fat. Their ER was higher than predicted. The higher overall efficiency of lambs on strategy M was explained by differences in the ratio of protein: fat deposited and maintained by lambs on each strategy. The EB composition of all slaughtered lambs was within the limits for published data. Non-carcass composition could be used to predict EB composition. The results highlight the importance of the factors mentioned in determining the efficiency of lambs on each strategy.

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Participation in contributing content to online communities remains heavily skewed. Yet little research has focused on lowering the contribution effort. I describe a general approach to facilitating user-generated content within the context of Wikipedia. I also present the IntelWiki prototype, a design and implementation of this approach, which aims to make it easier for users to create or enhance the free-form text in Wikipedia articles. The IntelWiki system i) recommends article-relevant reference materials, ii) draws the users' attention to key aspects of the recommendations, and iii) allows users to consult the recommended materials in context. A laboratory evaluation with 16 novice Wikipedia editors revealed that, in comparison to the default Wikipedia design, IntelWiki's approach has positive impacts on editing quantity and quality. Participants also reported experiencing significantly lower mental workload while editing with IntelWiki and preferred the new design.